Photospheric magnetic vector maps from two different instruments are used to
model the nonlinear force-free coronal magnetic field above an active region.
We use vector maps inferred from polarization measurements of the Solar
Dynamics Observatory/Helioseismic and Magnetic Imager (HMI) and the Solar
Optical Telescope Spectropolarimeter (SP) aboard Hinode. Besides basing our
model calculations on HMI data, we use both, SP data of original resolution and
scaled down to the resolution of HMI. This allows us to compare the model
results based on data from different instruments and to investigate how a
binning of high-resolution data effects the model outcome. The resulting 3D
magnetic fields are compared in terms of magnetic energy content and magnetic
topology. We find stronger magnetic fields in the SP data, translating into a
higher total magnetic energy of the SP models. The net Lorentz forces of the
HMI and SP lower boundaries verify their force-free compatibility. We find
substantial differences in the absolute estimates of the magnetic field energy
but similar relative estimates, e.g., the fraction of excess energy and of the
flux shared by distinct areas. The location and extension of neighboring
connectivity domains differs and the SP model fields tend to be higher and more
vertical. Hence, conclusions about the magnetic connectivity based on
force-free field models are to be drawn with caution. We find that the
deviations of the model solution when based on the lower-resolution SP data are
small compared to the differences of the solutions based on data from different
instruments.Comment: 8 pages, 10 figures, APJ, accepte
